This invention relates to an improved hot water supply system and particularly to such systems useful in residential and commercial structures in which hot water is demanded at a particular discharge point on an intermittent basis.
An age-old problem with hot water supply systems has been the necessity for the user to open the hot water valve and permit water to flow from the faucet or nozzle for a considerable period of time before hot water becomes available. This problem exists since the hot water source such as a water heater or boiler is typically located remotely from the point of discharge and is connected between these points by a long supply pipe. Hot water within the supply pipe loses its heat to the surrounding environment rapidly once the flow of water therethrough is stopped or significantly reduced. Once the water in the supply pipe has dissipated its heat, the hot water discharge valve must be opened to permit the water to flow until the cooled water is completely displaced from the connecting pipe. This requirement results in a significant inconvenience to the user and is also highly inefficient from an energy conservation perspective since every use results in the entire connecting pipe being filled with hot water which becomes cooled after the demand is fulfilled.
In many instances, a delay in availability of hot water is not objectionable. However, where the user desires a small quantity of hot water, for example, for hand and face washing in a home bathroom, such a delay constitutes an inconvenience and a significant waste of energy since the user only requires a few pints or gallons of hot water and yet the entire volume of the connecting supply pipe must be displaced with hot water before such a small quantity becomes available.
Numerous attempts have been made to address the problems of providing hot water quickly and overcoming the inherent inefficiencies of present day hot water supply systems. According to one approach, the hot water supply pipes are encased by a jacket of thermal insulating material. The use of insulation does prevent rapid loss of heat from heated water in supply pipes so that, if hot water is demanded soon after an initial demand, hot water will be immediately available. This approach, however, has the drawback that, following a sufficiently prolonged period of time, heat from the supply pipe will eventually be dissipated to the cooler surrounding environment necessitating the displacement of this cooled water before hot water can be discharged. In many usage conditions, there may be substantial lapses of time between demands for hot water, and therefore, this approach does not overcome the above-described shortcomings of present day hot water supply systems.
Another approach toward addressing the shortcomings of present hot water supply systems is the use of so-called point of source water heaters. These electrically or gas fired water heaters are located close to the point of hot water discharge. These devices rapidly heat water from a supply pipe to provide nearly instantaneous hot water. These heaters, however, suffer the disadvantages that they are costly, complicated, bulky, and generally require a significant amount of labor for installation.
A further method of addressing the above-mentioned problems is to locate the hot water heater or boiler as close as practicable to the desired point of hot water discharge, thereby minimizing the amount of water which must be displaced within a connecting supply pipe before hot water becomes available. This approach is unsatisfactory, however, where multiple points of hot water discharge are desired, such as in a typical home where several bathrooms or sinks may be located at various remote locations. In such situations, this method of overcoming the problems of present hot water supply systems is useful only for certain of the multiple hot water discharge locations. Moreover, the design of a particular structure may impose constraints on the placement of the water heater or boiler such that the use of long connecting pipes cannot be avoided.
Yet another approach toward minimizing the above-mentioned shortcomings is to employ a pipe between a hot water source and the point of discharge which is as short as possible and which has as small a diameter as possible, thereby minimizing the total retained volume of water which must be displaced in order to provide hot water once the retained water has cooled. This method, however, has limitations in that the diameter of the connecting pipe is primarily dictated by the maximum flow rate requirements of the system. For example, many hot water supply systems are used to provide a full residential bathroom including a sink and shower with hot water. This pipe connecting the hot water source with such a bathroom must have a sufficient flow rate capacity to supply the shower and sink during use. In such applications, the use of a small diameter hot water supply pipe would provide hot water more rapidly, but would be unable to fulfill the maximum flow rate requirements of the system.
In view of the above, it is an object of this invention to provide an improved hot water supply system which provides hot water quickly and with high efficiency. It is a further object of this invention to provide such a hot water supply system inexpensively and without complex apparatus. It is an additional object of this invention to provide an improved hot water supply system which is readily adaptable for use with existing hot water supply systems.
The above principal objects of this invention are achieved by providing a hot water supply system which employs a pair of pipes which connects the source of hot water with the point of hot water discharge. Valve means are employed which permit water flow only through one of the pipes, termed an auxiliary pipe, in situations wherein a small quantity of hot water is desired. When high flow rates of hot water are required, the valve permits flow through both the auxiliary and primary hot water pipe. The auxiliary pipe has a smaller diameter than is dictated by the maximum flow rate requirements of the outlet and therefore has a lower retained volume which is quickly displaced, enabling hot water to be available without a long delay. When high volumes of water are required, the valve means permits flow through the primary pipe to fulfill the maximum flow rate requirements for the particular point of discharge. In situations where only a small volume of hot water is demanded, water flows only through the auxiliary pipe and, due to its small cross-sectional area, it retains a smaller volume of hot water, and therefore less energy is lost when the heat retained by this water is dissipated to the environment during prolonged periods wherein the flow rate within the pipe is zero or minimal.
Several embodiments utilizing the above-mentioned approach toward providing an improved hot water supply system are described in detail in the above referenced related patent application. This particular disclosure is related to a number of improvements and alternate embodiments for the systems described in the above referenced application. In accordance with the present invention, an automatic valve means is described which senses the flow rate being demanded at the water discharge outlet and automatically switches between the auxiliary and primary water supply pipes in accordance with the discharge rate being demanded. This valve means may be in the form of a pressure reducing valve within the primary pipe flow which permits flow therethrough when the pressure in the auxiliary pipe falls below the predetermined level. Accordingly, once the user is demanding a flow rate which exceeds the capability of the auxiliary pipe, the flow is automatically augmented by the primary supply pipe. The present disclosure further describes a flow pulser which may be placed in the primary water supply line to provide an indication to the user that the flow through the primary pipe is occurring. When used with a manual valve such as described in the above-referred application, the flow pulser enables the user to allow flow only through the auxiliary pipe, or both pipes, as desired. In those situations where residential water pressure is extremely low such that an adequate flow rate through the auxiliary water pipe cannot be provided, this invention teaches the use of an in-line water pump which would aid in providing such flow.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.